Nanowires for heat conversion

Abstract

This review focuses on the investigation and enhancement of the thermoelectric properties of semiconducting nanowires (NWs). NWs are nanostructures with typical diameters between few to hundreds of nm and length of few to several µm, exhibiting a high surface-to-volume ratio. Nowadays an extraordinary control over their growth has been achieved, enabling also the integration of different type of heterostructures, which can lead to the engineering of the functional properties of the NWs. In this review we discuss all concepts which have been presented and achieved so far for the improvements of the thermoelectric performances of semiconducting NWs. Furthermore, we present a brief survey of the experimental methods which enable the investigation of the thermoelectric properties of these nanostructures.

Spatially resolved thermoelectric effects inoperandosemiconductor–metal nanowire heterostructures

“…In order to take into account the above described microscopic extension of the Peltier coefficient we consider the temperature profile beyond the length scale away from the Al-Ge interface. Then we can treat the temperature profiles as solutions to eqn (5) eqn (7). By extrapolating the exponential fit we conceptually concentrate the extended heat source in a point at the AlGe interface.…”

“…[1][2][3] Particularly interesting realizations are axial and radial nanowire heterostructures, combining effects of reduced dimension both in the transport direction and perpendicular to it. [4][5][6] While (infinitely) long thermoelectric elements are well studied, there is little understanding of situations in which the length of the thermoelectric is on the order of carrier scattering lengths. For example, the influence of interfaces between a thermoelectric material and metallic contacts or the transition between the conventional Peltier effect and thermionic emission are lacking insights in the experimental realization.…”

“…The thermal contacts to nanowire samples, for example, have turned out to be a major issue. 5,8 It has been proposed that this can be mitigated using extended measurement series for example of thermal transport as a function of length, sometimes called transmission line method 9 or related. 10 Apart from being time-intensive, these solutions rely on other assumptions such as the ability to fabricate reproducible test structures with the same contact resistances to electrodes or thermometers.…”

Measuring the Optical Absorption of Single Nanowires

“…In recent years, nanowires (NWs) have emerged as promising building blocks for applications in the field of electronics [1][2][3], energy conversion [4,5], and optoelectronics [6][7][8], among others [9,10]. The wide range of applicability of NWs stems first of all from their geometry, which can alter mechanical, electronic, as well as optical effects [11,12], but also from the possibility to grow materials with crystal structures that are unstable in bulk [13][14][15] and have different electronic [16,17] and phononic [18,19] properties from their bulk counterparts.…”

Special issue on thermoelectric properties of nanostructured materials

“…The first one, by Kim and coworkers, deals with the experimental methods to obtain reliable estimates of the thermoelectric parameters at the nanoscale [2]. In the other Swinkels and Zardo give a detailed account of the role of semiconducting nanowires in both fundamental studies of thermoelectric effect and in emerging thermoelectric devices [3].…”